Process for conversion of hydrocarbons



Nov. 10, 1964 J. C. TRANTHAM ETAL PROCESS FOR CONVERSION OF HYDROCARBONS Filed COMBUSTION PROPAGATION N July 22,- 1960 HYDROCARBON CHARGE l0 SAND OR OTHER CATALYST BED =aa "COOLING con.

24 *COMBUSTION ZONE --COOLING COIL To PRODUCT RECOVERY INVENTORS. -J. c. TRANTHAM c. J. ENGLE BY A. R. SCHLEICHER A TTORNEYS I United States Patent PROCESS FOR CONVERSION OF HYDRGCARBON .loseph C. Trantharn and Charles J. Eagle, Bartlesvilie,

Okla, and Arthur R. Schieicher, Champaign, Iih, as-

signors to Phillips Petroleum Company, a corporation of Delawme Filed July 22, 1960, Ser. No. 44,722 17 Claims. (Cl. 208-120) This invention relates to an improved process for the conversion of hydrocarbons to more desirable products.

In conventional refining processes the hydrocarbon feed is either preheated and passed over a catalyst or contacted with hot catalyst in a fluidized bed. In either case, the feed and/or catalyst are heated by means of heat exchangers and do not actually come into intimate contact with any combustion process. In catalytic refining processes and in processes involving the synthesis and production of complex organic compounds, the cost of catalytic converters and heat exchange equipment adds considerably to the cost of the processes. This invention is concerned primarily with a more economical and improved method or process for the conversion of hydrocarbons to more valuable hydrocarbons and to complex organic compounds, such as oxygenated hydrocarbons and other oxygenated products.

Accordingly, the principal object of the invention is to provide an improved process for the conversion of hydrocarbon materials to more desirable products. An other object is to provide an improved process for upgrading and refining hydrocarbon materials. A further object is to provide an efficient process for converting crude oil to lighter hydrocarbon materials including gasoline boiling range hydrocarbons. It is also an object of the invention to provide a process for the conversion of hydrocarbons found in crude oil to azulene. Other objects of the invention will become apparent to one skilled in the art upon consideration of the accompanying disclosure.

A broad aspect of the invention comprises mixing a suitable hydrocarbon feed with air or other oxidizing gas, such as diluted air, O -enriched air, or substantially pure oxygen, and introducing the mixture into a combustion zone in a porous or permeable bed of particulate refractory solids, preferably one with catalytic properties. A minor proportion of the hydrocarbon material is con sumed by the combustion by regulating the proportion of oxygen in the mixture so as to maintain the desired temperature in the combustion zone of the bed. Combustion temperatures are preferably maintained in the range of 900 to 1200 F., as these have been found to be highly efficient in laboratory scale combustion tests. The combustion consumes a minor proportion of the hydrocarbon material and the remainder is cracked and converted to lighter molecular weight hydrocarbons and oxygenated compounds. The produced liquids and gases are separated by conventional methods.

The hydrocarbon feed may comprise practically any hydrocarbon material. Even normally gaseous hydrocarbons may be converted to ethylene, acetylene, and oxygenated products in accordance with the invention. Generally speaking, subjecting a straight chain aliphatic hydrocarbon to thermal cracking merely results in breaking the molecule up into fragments consisting principally of lower molecular weight olefinic and aliphatic hydrocarbons. We have found in tests that by charging a substance such as n-cetane in admixture with air to a sand-packed column in which a combustion zone is maintained, other products can be obtained. In one such test, using 292 grams of n-cetane on Torpedo sandstone in. an inverse burning process, the products included a blue liquid material identified as a concentrate of azulene,

ice

which is a blue solid melting at 99 C. Azulene is an isomer of naphthalene and has the formula C H It is the parent substance of a group of coloring matters obtained from certain essential oils by oxidation. In addition, other higher molecular weight substances including aromatic hydrocarbons and their oxygenated products were produced. Azulene was also produced in an inverse in situ combustion of a tar sand in field operaticns.

Laboratory tests in which heavy crude oils and tars were partially combusted in a bed of silica show that the process greatly reduces viscosity and molecular weight of the oils. The sulfur content of the effiuent product was greatly reduced and a large proportion of the product is in the gasoline and gas oil ranges.

A more complete understanding of the invention may be had by reference to the accompanying schematic drawing in which numeral it designates a reaction vessel or catalyst case which is packed with a permeable bed 12 comprising solid particulate refractory material which is preferably catalytic with respect to hydrocarbons. Silica in the form of sand, activated clay (aluminum silicate) synthetic silica, synthetic silica-alumina, synthetic alumina, activated bauxite, and such materials, alone or having other catalytic materials deposited thereon are suitable for use as the permeable bed. Catalytic material which can be incorporated in the bed include the iron group metals (Ni, Co, Fe) and their oxides. Cu, Ivin, Mo, Cr, U, and V and their oxides are also suitable for including in the catalytic materials in minor amounts, such as 0.15 to 10 weight percent.

Reactor it may be a high temperature alloy vessel or a carbon steel vessel provided with a refractory brick lining.

According to one aspect of the invention a section of the bed designated 14 is heated to combustion supporting temperature by any suitable means such as burning therein a combustible mixture of gaseous hydrocarbon (propane) and air injected through line i6 and ignited as it reaches the opposite end of the bed in section 14. The hydrocarbon feed may also be the feed to be converted. When section 14 has been raised to combustion supporting temperature such as a temperature of at least 600 or 700 F, the feed to be converted is introduced through line 13 and admixed with air introduced through line 26), the air being of lesser proportion than that required for complete combustion of the hydrocarbon feed. The mixture passes through line 16 and through the bed 12 so that it is burned in section 14. Continuous burning of a portion of a hydrocarbon in section 14 with regulation of the proportion of air in the mixture causes the combustion zone to move toward the opposite end of the packed bed. By p0sitioning thermocouples 22 at spaced intervals along the bed, the location of the combustion zone can be observed at any time. When combustion zone 24 arrives at the position shown in the drawing, it can be stabilized in this area by proper regulation of the flow rate of air and/ or fuel into the bed. Effluent products are recovered from the reactor through lines 26 and 27 and are passed to product recovery means not shown.

The rate of air injection for any given feed injection rate can be varied to move the combustion zone by direct drive (cocurrently with the feed) or by inverse drive (countercurrently to the flow of feed). High flow rates of air result in moving the burning zone by direct drive while low flow rates of air move the burning zone inversely to the flow of feed. The rates of flow required can be determined for each feed by observation of thermocouples 23.

Another aspect of the invention comprises continuing the injection of the combustible mixture of hydrocarbon and air through line 16 at such a rate of air flow and proportion of air to hydrocarbon as to cause the combustion zone 24 to move completely through the bed countercurrently to the flow of combustible mixture and, when the combustion zone arrives at the injection end of the bed, terminating the how of the mixture through line 16 and then injecting hydrocarbon feed through line 30 and air through line 32 in such proportions that combustion zone 24 reverses itself and moves toward the opposite end of the bed inversely to flow of said feed. In this embodiment of the invention, it is usually necessary to inject liquid feed into the bed at reversal as it has the effect of cooling the bed in the injected end so that combustion is not immediately effected therein. In this manner, the feed (air and hydrocarbon) is raised in temperature as it moves through the bed until it reaches the hottest part thereof at the opposite end from the in jection end. After cooling the major portion of the bed down by injection of the hydrocarbon feed in liquid form, the hydrocarbon feed is then injected in vapor form by preheating or vaporizing the feed in a heat exchanger not shown. During the reverse burning, the effluent products are recovered through lines 16 and 34 and the burning zone is progressively moved to the injection end of the bed. The cycle of passing the com bustion front back and forth through the permeable bed is then repeated.

In accordance with another embodiment of the invention, the combustion zone may be positioned as shown in the drawing in accordance with the foregoing proce dure and after this has been effected, a coolant is circulated through cooling coils 36 and (These cooling coils are not incorporated in the bed when this embodiment of the invention is not to be used.) Circulation of coolant through coils 36 and 38 by means well known in the art prevents the refractory material surrounding the coil from heating sufriciently to permit the movement of a combustion front or zone through the cool material. In this manner the combustion zone is restricted to a well defined area intermediate the cooling coils.

The following examples are presented to illustrate the invention and are not to be construed as unnecessarily limiting the same.

Example I A sand pack in a 2" stainless steel combustion tube containing 2919 g. of Barnsdall Sand was impregnated with percent by weight n-cetane. The porosity of the pack was 41.7%, and cetane saturation was 54.3%. The original gas permeability was 2.8 darcys. It was ignited by counterfiow technique (i.e., heated to 1000 F. at the sand face and then air was injected from the opposite end of the tube) and was burned countercurrently at an air flux of 300 s.c.f./hr./ft. The combustion temperature averaged about 1050 F. at this air flow rate, the CO content of the exhaust gas was about 12% and the CO content was around 1.9%.

Distillation of the liquid product gave 19.5% by volume of material boiling below cetane (287.5 C.). From this cut a small amount of a blue compound identified as azulene was separated by silica gel chromatography. Gas chromatography showed the presence of about 8 percent of the various l-oleiins from C to C Example of combustion where location of cumbustion zone was controlled by regulation of fuel feed rate:

Example II A 2-inch stainless steel tube, equipped with thermocouples TC TC was packed with clean, unconsolidated, round-grain sand (spittoon sand) and it was flooded with North Burbank Unit oil (about 38 API gravity) until saturated, The excess oil was then swept out with air until the oil came out as occasional drops. Because of previous difficulties in igniting oil of this high gravity either by cocurrent or countercurrent air flow a section of approximately 2 inches of Clear Creek Tar Sand was packed adjacent the electrical igniter and this tar sand was ignited by heating to 580 F. at TC in a stream of nitrogen and then passing air cocurrently at 340 s.c.f./ hr./ft. through the heated tar sand. When the fire front approached the discontinuity between the tar sand and the oil-saturated sand, the air flow was reversed. The combustion continued by countercurrent burning and the temperature at TC rose rapidly to 1300 F. It then rose gradually to a maximum at 1800 F. At this point, the air flux was reduced to 183 s.c.f./hr./ft. and the temperature at TC went through another maximum at 1480 F. The behavior of the temperature at TC indicated that the higher air flux prevailing immediately after the air direction was reversed moved too much of the liquid fuel into the fire zone and drove it back towards TC Thus TC went through a maximum as the fire front passed it moving in the direction of the air llow. When the air flux was reduced, liquid fuel was allowed to remain in place while air was fed to the tire zone. This caused the fire to burn countercurrently past TC (resulting in a second maximum) seeking fuel. The second maximum was broad, indicating a slow movement of the fire zone. Since the direction of movement was varied at will by varying the air flux, an air flux can be found which will maintain the fire zone stationary during countercurrent burning.

Certain modifications of the invention will become apparent to those skilled in the art and the illustrative details disclosed are not to be construed as imposing unnecessary limitations on the invention.

We claim:

1. A process for upgrading and converting hydrocarbons to more desirable products which comprises providing a stationary particulate elongated bed of solid refractory material within an elongated reaction chamber occupying substantially the entire reaction zone therein; heating a complete transverse cross section of said bed at one end thereof to combustion-supporting temperature; forming a mixture of said hydrocarbons and air in which the air concentration is substantially less than that required for complete combustion of said hydrocarbons and at a temperature below combustion temperature; thereafter passing said mixture into the hot section of said bed so as to ignite same and establish a combustion zone throughout said cross section, thereby burning a substantial proportion of said hydrocarbons so as to maintain the temperature of said zone in the range of 900 to 1200 F. and convert within said bed a substantial proportion to lighter hydrocarbons and oxygenated products; regulating the flow rate of said mixture and the proportion of air therein so as to move a relatively thin combustion zone through said bed toward the opposite end thereof; and recovering said hydrocarbons and products from one end of said bed.

2. The process of claim 1 wherein said combustion zone is moved to a section of said bed intermediate its ends and maintained there by regulating the flow rate of said mixture and the proportion of air therein, and products are recovered from the opposite end of said bed.

3. The process of claim 2 wherein said mixture is passed through said bed from the ignited end and said zone is caused to move into said intermediate section by controlling the rate of flow of air in relation to the rate of flow of hydrocarbons in said feed.

4. A process for the conversion of hydrocarbons which comprises establishing a hot zone at a temperature above combustion temperature of said hydrocarbons in one end of an elongated permeable stationary bed of particulate solid refractory material occupying substantially the entire reaction zone in a reaction chamber; forming a combustible mixture of hydrocarbons and air outside of said bed at a temperature below combustion temperature and passing same through said bed from the other end into said zone, said air being substantially less than that required for complete combustion of the hydrocarbons in said mixture so as to establish a combustion zone and burn a substantial proportion of said hydrocarbons and convert a substantial proportion to other hydrocarbons and oxygenated products; regulating the ratio of air to hydrocarbons in said mixture so as to cause said combustion zone to travel through said bed to said other end; and recovering products from said one end.

5. The process of claim 4 including the steps of changing the flow of said mixture into said bed to said one end when said combustion zone arrives adjacent said other end, thereby causing the combustion zone to reverse through said bed to said one end, and recovering products from said other end during the reverse travel of said zone.

6. The process of claim 1 wherein said bed comprises a conversion catalyst.

7. The process or" claim 1 wherein said bed comprises a cracking catalyst.

8. The process of claim 7 wherein said catalyst comprises silica.

9. The process of claim 7 wherein said catalyst comprises silica and an iron group metal oxide.

10. The process of claim 7 wherein said catalyst comprises silica-alumina.

11. The process of claim 1 wherein said combustion zone is moved to and maintained in an intermediate section of said bed by circulating a coolant through a transverse section of said bed in indirect heat exchange therewith on each side of said combustion zone.

12. The process of claim 1 wherein said feed is a crude oil.

13. The process of claim 1 wherein said feed is a gas oil.

14. The process of claim 1 wherein said feed is a gasoline boiling range stock.

15. The process of claim 1 wherein said hydrocarbons include n-cetane and azulene is produced and recovered. 16. A process for converting hydrocarbons to more desirable products which comprises packing an elongated bed of particulate refractory solids into a reaction zone so that said bed occupies substantially the entire reaction zone; saturating said bed with a hydrocarbon oil; igniting one end of said bed by heating same to above ignition temperature of said oil and injecting air free of fuel into the heated area; continuing the injection of fuel-free air so as to burn a substantial portion of the oil and convert within said bed a remaining portion of said oil to lighter hydrocarbons and oxygenated products; and recovering the converted hydrocarbons from said bed.

17. The process of claim 16 wherein said oil is a high gravity oil which is difficult to ignite and ignition is e1- fected by packing a tar sand into the ignition end of said bed, heating said sand to above ignition temperature, injecting air into the ignited sand from said ignition end so as to burn through to the inner end of the tar sand pack, and thereafter reversing the flow of air so that it enters the opposite end of said bed.

References Cited in the file of this patent UNITED STATES PATENTS 1,295,825 Ellis Feb. 25, 1919 2,222,489 Riggs Nov. 19, 1940 2,476,729 Helmers July 19, 1949 2,645,606 Hepp July 14, 1953 2,752,407 Cahn June 26, 1956 2,809,981 Kittleson et al. Oct. 15, 1957 2,824,148 Kenlemans et al. Feb. 18, 1958 2,967,205 Coherly Jan. 3, 1961 2,967,878 Fenske et a1 Jan. 10, 1961 3,006,944 Fenske et al Oct. 31, 1961 

1. A PROCESS FOR UPGRADING AND CONVERTING HYDROCARBONS TO MORE DESIRABLE PRODUCTS WHICH COMPRISES PROVIDING A STATIONARY PARTICULATE ELONGATED BED OF SOLID REFRACTORY MATERIAL WITHIN AN ELONGATED REACTION CHAMBER OCCUPYING SUBSTANTIALLY THE ENTIRE REACTION ZONE THEREIN; HEATING A COMPLETE TRANSVERSE CROSS SECTION OF SAID BED AT ONE END THEREOF TO COMBUSTION-SUPPORTING TEMPERATURE; FORMING A MIXTURE OF SAID HYDROCARBONS AND AIR IN WHICH THE AIR CONCENTRATION IS SUBSTANTIALLY LESS THAN THAT REQUIRED FOR COMPLETE COMBUSITON OF SAID HYDROCARBONS AND AT A TEMPERATURE BELOW COMBUSTION TEMPERATURE; THEREAFTER PASSING SAID MIXTURE INTO THE HOT SECTION OF SAID BED SO AS TO IGNITE SAME AND ESTABLISH A COMBUSTION ZONE THROUGHOUT SAID CROSS SECTION, THEREBY BURNING A SUBSTANTIAL PROPORTION OF SAID HYDROCARBONS SO AS TO MAINTAIN THE TEMPERATURE OF SAID ZONE IN THE RANGE OF 900* TO 1200*F. AND CONVERT WITHIN SAID BED A SUBSTANTIAL PROPORITON TO LIGHTER HYDROCARBONS AND OXYGENATED PRODUCTS; REGULATING THE FLOW RATE OF SAID MIXTURE AND THE PROPORTION OF AIR THEREIN SO AS TO MOVE A RELATIVELY THIN COMBUSTION ZONE THROUGH SAID BED TOWARD THE OPPOSITE END THEREOF; AND RECOVERING SAID HYDROCARBONS AND PRODUCTS FROM ONE END OF SAID BED.
 7. THE PROCESS OF CLAIM 1 WHEREIN SAID BED COMPRISES A CRACKING CATALYST.
 10. THE PROCESS OF CLAIM 7 WHEREIN SAID CATALYST COMPRISES SILICA-ALUMINA. 